Apparatus and method to determine pinion angle of drive train

ABSTRACT

Apparatus for use in determining the pinion angle of the differential or transmission of a motor vehicle includes an attachment which is detachably mountable to the input shaft or the output shaft. A camber gauge having longitudinal levels is detachably mounted to the attachment to measure the attitude of the differential or the transmission to which it is mounted.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a division of and claims priority from utility patentapplication entitled “Apparatus for use in Assembling Drive Train of aRace Car”, Ser. No. 10/630,272 filed Jul. 30, 2003, now U.S. Pat. No.6,804,897, which claimed priority from provisional patent applicationentitled “Apparatus for Use in Assembling Drive Train of a Race Car”,Ser. No. 60/402,442 filed Aug. 9, 2002. The disclosures of utilitypatent application Ser. No. 10/630,272 filed Jul. 30, 2003, andprovisional patent application Ser. No. 60/402,442 are herebyincorporated in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

BACKGROUND OF THE INVENTION

In the assembly of race cars with rear wheel drive with a differentialgear in the rear and engine and transmission in the front of the racecar, it is necessary to align the axis of the output shaft of thetransmission with the input shaft of the differential gear to avoidvibration and to improve performance. Current practice for aligning theaxis of the transmission output shaft with the input shaft of thedifferential gear has been by trial and error and through observations.A need exists for an improved alignment system to facilitate properpositioning of the differential input shaft relative to the transmissionwhen a race car is being assembled.

BRIEF SUMMARY OF THE INVENTION

An apparatus for use in assembling the drive train of a race car isdisclosed.

The present invention provides apparatus for use in aligning thedifferential input shaft of a race car with the transmission outputshaft of the race car. With the drive shaft removed from the drivetrain, a transmission attachment is detachably mountable to thetransmission of the race car in place of the drive shaft. Thetransmission attachment includes a plate mounted to a shaft whichextends axially from the plate. The shaft may be coupled with the outputshaft of the transmission by its being received on the output shaft ofthe transmission. A first laser is mounted in a central opening in theplate such that the laser will emit a light beam aligned with the axisof the output shaft of the transmission. The plate includes concentricmarkings on its face which are centered on the central opening.

A second part of the apparatus is a differential input shaft attachmentwhich may be mounted to the differential input shaft assembly while thedrive shaft of the race car is removed from its coupling to thedifferential gear. The differential input shaft attachment may bemounted to the differential yoke which is coaxially mounted to the inputpinion shaft of the differential gear. The differential input shaftattachment includes a plate which is mountable to the differential yokesuch that the plate is perpendicular to the axis of the input pinionshaft of the differential. The plate of the differential input shaftattachment has a second laser mounted within a central opening in theplate. The second laser will emit a light beam aligned with the axis ofthe input pinion shaft of the differential input shaft and directedtoward the transmission. The second plate also includes concentricmarkings on its face which are centered on the central opening.

When the lasers are activated, adjustment of the orientation of thedifferential input shaft centerline relative to the transmission can becarried out by moving the differential gear or the rear of thetransmission to a position where the beams from the first and secondlasers are not intersecting. The concentric markings on the plates allowthe user to easily assess the distance from the center of the plate atwhich the opposing laser beam is striking the plate. By introducing afine dust from a powder such as corn starch or the like into the regionbetween the plates, the laser beams can be observed and adjustment ofthe differential input shaft can be accomplished to the point where thelaser beams do not intersect. With the input shaft of the differentialinput shaft aligned with or parallel with the output shaft of thetransmission of the race car, optimum performance of the drive train isobtained. The first laser may be identical and interchangeable with thesecond laser and each may emit a red beam. However, lasers which emitdiffering beam colors may be employed in order to differentiate thelaser of the transmission attachment from the laser of the differentialinput shaft attachment.

The apparatus may also be used to analyze alignment of the differentialinput shaft to the transmission through the range of vertical motion ofthe differential input shaft permitted by the race car's suspension.This may be done while the race car remains stationary by mechanicallylifting the differential input shaft relative to the race car's chassiswhile the transmission attachment and the differential input shaftattachment remain temporarily attached to the transmission and thedifferential input shaft respectively. In this manner, the alignment ofthe differential input shaft to the transmission output shaft can beinspected throughout the range of vertical motion of the differentialinput shaft.

In a variation of the invention, either laser may be removed from thecentral opening of the plate in which it is installed and a targetelement may be placed in the central opening in its place. The targetelement has a center indentation or other centered target mark for usewhen the user desires to reposition the transmission or differentialinput shaft such that the laser mounted to the one of the gearassemblies is aligned exactly with the axis of the other gear assembly.

In another variation, the laser of either attachment may be removed andreplaced with an adapter which allows measurement of the pinion angle ofthe differential input shaft or the transmission of the race car bymounting a standard camber gauge in axial alignment with thedifferential input shaft or the transmission output shaft depending onwhich gear assembly is to be tested. The camber gauge which may be usedfor this measurement is a typical gauge used to mount to the spindle ofa vehicle wheel to measure the camber (tilt from vertical) of the wheeland includes a first transverse level which can be used to place thecamber gauge in a horizontal orientation relative to its short axis. Apair of longitudinal elongate bubble levels are positioned parallel tothe long axis of the camber gauge and will indicate the decline orincline from horizontal, in degrees, of the shaft of the gear assemblywhose attitude is being measured. With the use of this variant of theinvention, the pinion angle of the differential input shaft or of thetransmission can be compared with the angle present when thedifferential input shaft and transmission have been accurately alignedby use of the primary system using opposing lasers as described above.

It is a primary object of this invention to provide apparatus for use inaccurately aligning the differential input shaft with the transmissionof a race car during the assembly of the race car drive train.

It is also an object of the invention: to provide an easily mounted andused apparatus for detection of non-parallel alignment of the outputshaft of the transmission with the input shaft of the differential gearof a race car; to provide an adaptable apparatus which permits visualdetection at the differential of a race car of an emitted laser beam ofa laser aligned with the axis of the output shaft of the transmission ofthe race car, or to allow visual detection at the transmission of anemitted laser beam of a laser aligned with the input shaft of thedifferential of the race car; and to provide an adaptable apparatuswhich permits axial attachment of a camber gauge to the output shaft ofa transmission of a race car to measure the pinion angle of the outputshaft of the transmission; to provide an adaptable apparatus whichpermits axial attachment of a camber gauge to the input shaft of adifferential gear of a race car to measure the pinion angle of the inputshaft of the differential gear.

These and other objects of the invention will become apparent fromexamination of the description and claims which follow.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is a schematic representation of the invention in use to alignthe differential input shaft with the transmission of a race car.

FIG. 2 is a perspective of the differential input shaft attachment ofthe invention mounted to the differential yoke of a differential gearassembly.

FIG. 3 is a perspective of the transmission attachment of the inventionwhich is detachably mountable to the transmission of a race car.

FIG. 4 is a front elevation of the attachment of FIG. 2.

FIG. 5 is a side plan view of the plate member of the attachment of FIG.2.

FIG. 6 is a front elevation of the attachment of FIG. 3 with part of theshaft cut away.

FIG. 7 is a side plan view of the plate member of the attachment of FIG.3.

FIG. 8 is a enlarged front elevation of the laser assembly of theattachments of FIGS. 2 and 3.

FIG. 9 is a side plan view of the laser assembly of FIG. 8.

FIG. 10 is an enlarged perspective of a target member which may besubstituted for the laser assembly of the attachments of FIGS. 2 and 3.

FIG. 11 is a top plan view of a camber gauge which may be mounted inplace of the laser assembly of the attachments of FIGS. 2 and 3.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an apparatus to align the axiallyrotatable input shaft (not shown) of the differential gear 5 of a racecar with the axially rotatable output shaft (not shown) of thetransmission 7 of the race car. FIG. 1 illustrates the invention mountedto the transmission 7 and differential gear 5 of a race car.Transmission attachment 8 is detachably mounted to the transmission 7such that transmission attachment 8 is coupled to the output shaft ofthe transmission 7 and is coaxial therewith. Differential attachment 6is detachably mounted to the differential yoke 9 of the differentialgear 5 such that differential attachment 6 is coupled to the input shaftof the differential gear 5 and is coaxial therewith. Differentialattachment 6 includes laser assembly 16 which selectively emits lightbeam 15. Transmission attachment 8 includes laser assembly 26 whichselectively emits light beam 17. When the differential gear 5 andtransmission 7 are properly aligned, light beam 17 will strikedifferential attachment 6 while light beam 15 will strike transmissionattachment 8 and light beams 15 and 17 will not intersect.

Referring now to FIGS. 2, 4, and 5, differential attachment 6 comprisesa first plate 10 detachably mounted perpendicularly to differential yoke9 which is coaxially mounted to the input shaft of the differential gear5 of the race car. Plate 10 is preferably hexagonal but may be round,octagonal, or another shape. Differential attachment 6 further comprisesa first laser assembly 16 which includes a cylindrical body 18 which ismounted to first plate 10, the laser assembly 16 selectively emitting afirst light beam 15 directed away from the differential yoke 9 in adirection substantially perpendicular to the plane of the first plate 10and coaxial with the axis of the differential yoke 9 and the input shaftof the differential gear 5. Plate 10 with first laser assembly 16mounted thereto may be selectively detachably mounted to yoke element 14by screws 64 passed through holes 66 in plate 10.

First laser assembly 16 is illustrated in detail in FIG. 8 wherein it isseen that first laser assembly 16 comprises a laser housing 42 mountedcoaxially to cylindrical body 18. Laser housing 42 houses first laser11. Cylindrical body 18 is provided with a switch handle 52 which may beused to manually activate first laser 11. Cylindrical body 18 includes athreaded extension 54 which is matable with internal threading of thecentral opening 12 of first plate 10 to mount first laser assembly 16 tofirst plate 10.

Referring to FIGS. 3, 6, and 7, transmission attachment 8 comprises asecond plate 20, a second laser assembly 26 and a coupling shaft 24.Second plate 20 may be identical in shape to first plate 10 ofdifferential attachment 6 but need not be. Second plate 20 is mountedcoaxially to shaft 24, the shaft 24 receivable coaxially on the outputshaft (not shown) of the transmission 7 of the race car. A second laserassembly 26 is mounted coaxially to the second plate 20 and includes asecond cylindrical body 28. Second laser assembly 26 is mountable tocentral opening 22 of second plate 20 as seen in FIG. 7. Second laserassembly 26 is manually operable to selectively emit a second light beam17 directed away from the transmission, at a substantial perpendicularto the plane of the second plate 20 and coaxial with the shaft 24 whichmay axially couple to the output shaft of the transmission 7.

Concentric circular markings 60, 62 and 61, 63 may be etched or drawn onplates 10, 20 respectively to provide indication of the impingement oflight beams 17, 15 thereon respectively.

It is to be understood that in the preferred embodiment, second laserassembly 26 is physically identical to the first laser assembly 16 seenin FIGS. 8 and 9, though it is not required that each be identical tothe other.

In the preferred embodiment, each laser assembly 16, 26 emits a redlight beam 15, 17. Alternatively, first laser assembly could emit lightbeam 15 of a different color than the color of light beam 17 of secondlaser assembly 26.

The differential attachment 6 may be selectively mounted to the inputshaft of the differential gear 5 of the race car by mounting plate 10 tothe yoke element 14 of the differential yoke 9 of differential gear 5.The transmission attachment 8 may be selectively coupled to the outputshaft of the transmission 7 by sliding the coaxial shaft 24 onto thetransmission output shaft (not shown), splines 42 therein meshing withcomplementary splines on transmission output shaft. Plates 10, 20 serveas targets for light beams 17, 15. The first light beam 15 from thefirst laser assembly 16 is directed toward the second plate 20 when thefirst laser 15 is activated. The second light beam 17 from the secondlaser assembly 26 is directed opposingly to the first light beam 15 topreferably strike the first plate 10. If transmission 7 and differentialgear 5 are in general alignment, first light beam 15 will strike secondplate 20 and second light beam 17 will strike first plate 10.

The differential attachment 6 may be mounted to the differential yoke 9contemporaneously with mounting of the shaft 24 of transmissionattachment 8 to the transmission output shaft of transmission 7. Bothfirst laser assembly 16 and second laser assembly 26 may then beactivated and a fine particulate such as a powder (for example, cornstarch) may be introduced into the space between the first plate 10 andsecond plate 20. When the laser assemblies 16, 26 are activated, thelight beams 15, 17 from each laser assembly 16, 26 may be observed asthey strike the fine particulate and as they strike the opposing plates20, 10. The differential input shaft orientation may be adjusted suchthat the beams 15, 17 from the laser assemblies 16, 26 are parallel ifnot coincident. By avoiding convergence or intersection of the two lightbeams 15, 17 between first and second plates 10, 20, desired alignmentof the differential gear 5 to the transmission 7 may be achieved.

While transmission attachment 8 remains mounted to the output shaft oftransmission 7 of the race car and while differential attachment 6remains mounted to the input shaft of differential gear 5, the user maymechanically raise the differential gear 5 relative to the race carchassis or raise the race car chassis relative to the rear axle of therace car to determine if the alignment of the differential gear 5 to thetransmission 7 remains satisfactory throughout the vertical range ofmotion of the differential gear 5. The laser assemblies 16, 26 may beactivated at any stage of the lifting of the differential gear 5 or therace car chassis to determine whether the light beams 15, 17 intersectand if so, further adjustment may be undertaken to properly align thedifferential gear 5 to the transmission 7.

If desired, one of laser assemblies 16, 26 may be replaced with a targetfixture 30 such as that shown in FIG. 10. On its rear face, targetfixture 30 includes a threaded stub (not shown) which may be received incentral opening 12, 22 of either first or second plates 10, 20. Thetarget fixture 30 includes a central target point such as indentation 32to provide a target location for the opposing laser aimed at targetfixture 30.

In an optional embodiment, either laser assembly 16, 26 may be removedfrom its plate 10, 20 and, either plate 10, 20 may be fitted with agauge 34 such as a camber gauge commonly used for adjusting camber of afront wheel of a vehicle. In the optional embodiment, gauge 34 may beused to measure the pinion angle of either the input shaft of thedifferential gear 5 or the output shaft of the transmission 7 of thevehicle. Referring to FIG. 11, it is seen that the gauge 34 includes atransverse bubble level 36 and longitudinal first and second elongatebubble levels 38 and 40. Elongate bubble levels 38, 40 are positionedsubstantially parallel to each other on the body 44 of gauge 34.Transverse bubble level 36 permits gauge 34 to be horizontally leveledon its short axis. First elongate level 38 is mounted on body 44 suchthat when the gauge 34 is in a position declining from horizontalrelative to its mounting end 46 (as illustrated in FIG. 11), the bubble48 of first level 38 will be located along the scale or at least spacedaway from the 0° mark 64 of first level 38. Second elongate level 40 ismounted such that when the gauge 34 is in a position ascending fromhorizontal relative to its mounting end 46, the bubble 50 of secondlevel 40 will be located along the scale or at least spaced from the 0°mark 66 of second level 40. When gauge 34 is maintained in an exacthorizontal orientation both longitudinally and transversely, each ofbubbles 48 and 50 will be at the respective 0° marks 64, 66 on first andsecond levels 38, 40 respectively.

Gauge 34 may be secured at its mounting end 46 to an adapter 56 whichincludes threaded bolt 58 which is receivable in central opening 12 ofeither first plate 10 or second plate 20. First plate 10 with gauge 34attached may be temporarily mounted to yoke element 14 of input shaft 9.Gauge 34 may be used to measure the cant from horizontal (the pinionangle) of the input pinion shaft of the differential gear 5 because thedifferential yoke 9 to which first plate 10 is mounted is axiallycoupled to the input shaft of the differential gear 5. When used withfirst plate 10, gauge 34 allows easy inspection for spacial orientationof the input shaft 9 of differential gear 5 to detect misalignment whichmay occur during transport or operation. If gauge 34 indicates that theattitude of the input shaft of differential gear 5 has changed from thatset from use of first and second laser assemblies 16, 26 as describedabove, then the gauge 34 may be removed from the first plate 10 and thelaser assembly 16 may be remounted in central opening 12 of first plate10 and transmission attachment 8 may be mounted to the transmissionoutput pinion shaft and aligning operations may be repeated.

Gauge 34 may also be substituted for laser assembly 26 of transmissionattachment 8 in order to measure the attitude of the transmission 7 inthe same manner as described above for using gauge 34 with differentialattachment 6.

Many variations of the invention will be apparent to those skilled inthe art. It is therefore to be understood, that within the scope of theappended claims, the invention may be practiced other than asspecifically described.

1. Apparatus to determine pinion angle comprising an elongate gaugedetachably mounted to extend from a rotatable shaft of a gear assemblyof a drive train of a race car, the gauge having a longitudinal axissubstantially coaxial with a longitudinal axis of the rotatable shaft,the gauge mounted to a plate, the plate substantially perpendicular tothe longitudinal axis of and detachably mounted to the rotatable shaft,the gauge including a pair of elongate levels generally parallel to theaxis of a gauge, the gauge including linear markings along each elongatelevel to indicate degrees of incline or decline, whereby the pinionangle of the gear assembly may be observed on the gauge.
 2. Theapparatus of claim 1 wherein the gauge has a transverse bubble level. 3.The apparatus of claim 1 wherein the gauge comprises a camber gauge. 4.Apparatus to determine pinion angle of a component of a drive traincomprising an elongate gauge detachably mounted to either an outputshaft of a transmission or an input shaft of a differential gear of amotor vehicle, the output shaft and the input shaft each having alongitudinal axis, the gauge having a longitudinal axis substantiallycoaxial with the longitudinal axis of the shaft to which the gauge ismounted, the gauge mounted to a plate, the plate substantiallyperpendicular to the longitudinal axis of and detachably mounted to theoutput shaft or the input shaft, the gauge including a pair of elongatelevels generally parallel to the axis of the gauge, whereby the pinionangle of the shaft to which the gauge is mounted may be observed on thegauge.
 5. The apparatus of claim 4 wherein the gauge includes atransverse bubble level.
 6. The apparatus of claim 4 wherein the gaugecomprises a camber gauge.
 7. Apparatus to determine pinion angle of ashaft comprising a gauge detachably mounted to extend from an outputshaft of a transmission of a motor vehicle, the gauge having alongitudinal axis substantially coaxial with the output shaft, the gaugemounted to a plate, the plate substantially perpendicular to alongitudinal axis of and detachably mounted to the output shaft, thegauge including at least one indicator responsive to the incline ordecline from horizontal of the output shaft.
 8. The apparatus of claim 7wherein the gauge further comprises a pair of longitudinal elongatebubble levels and a transverse level.
 9. Apparatus to determine pinionangle of a shaft comprising a gauge detachably mounted to extend from aninput shaft of a differential gear of a motor vehicle, the gauge havinga longitudinal axis substantially coaxial with the input shaft, thegauge mounted to a plate, the plate substantially perpendicular to alongitudinal axis of and detachably mounted to the input shaft, thegauge including at least one indicator responsive to the incline ordecline from horizontal of the input shaft.
 10. The apparatus of claim 9wherein the gauge further comprises a pair of longitudinal elongatebubble levels and a transverse level.
 11. A method to measure pinionangle of a drive train component comprising the steps of detachablymounting a gauge assembly to one of a transmission output shaft and adifferential input shaft of a motor vehicle, the gauge assemblycomprising an elongate camber gauge and a plate substantiallyperpendicular to a longitudinal axis of the elongate camber gauge,aligning the longitudinal axis of the camber gauge to be substantiallycoaxial with a longitudinal axis of the one of the transmission outputshaft and the differential input shaft wherein the plate is detachablymounted to one of the transmission output shaft and the differentialinput shaft, adjusting the elongate camber gauge so that it istransversely aligned with horizontal, reading the pinion angle byobserving bubble levels on the elongate camber gauge.